We are about to purchase a home that
has aluminum siding. Can aluminum siding be painted, and if so, what is the best way to
prime it and the best kind of paint?

Aluminum siding can certainly be
painted. Use a high quality paint (my favorite is Benjamin Moore, but be sure to use a
good one. With paint you really get whatyou pay for)

Go to the paint dealer and ask what
will work best for your tastes. You will need to clean it well first (renting a high
pressure washer will make short work of that job.. just be carefull with the pressure..
aluminum dents!) Appy the primer that is recommended for the paint you select. The dealer
will provide the best information here. Don't cut costs and the paint job will last.

What is the best (safest) way to
clean aluminum siding? Can scouring pads for Teflon pans be used?

Wow, scouring pads? It must be
dirty.. I would use TSP and hot water and a house cleaning brush. A pressure washer may
help but be very carefull with the pressure, it can dent the aluminum if you spray too
high a pressure too close to the siding.

I am planning to replace my existing aluminum siding with a new one. The salesman told me vinyl is better while others say aluminum is better. The salesman promise to give me same price for either one. Which one should I go?

O.K., they are both right... sort of. Aluminum is more expensive than vinyl, but it is readily available in a variety of colors. Aluminum is more labor intensive to install and you will pay more for installation. As with vinyl, aluminum expands and contracts but to a lesser degree. If you need to replace a piece of damaged aluminum you will need to remove every piece below it and one piece above it to do this.
Aluminum generally increases the value of your house more than vinyl.

Vinyl, on the other hand, has come a long way. You can get a great quality vinyl that will withstand the lawnmower rocks, etc. I would suggest a Norandex product. If you do damage a piece of vinyl you can easily remove that single piece.

If I were doing my home I would choose vinyl. But remember, you get what you pay for. Look at the premier brands and compare them to the cheaper ones, and I do mean cheaper. There is a big difference.

More
If I had the choice I would never get vinyl again. Sure aluminum can dent but vinyl cracks and makes holes that are not repairable. We have a few really good holes from stuff flying out the side of the lawn mower. To replace a whole section calls for us removing all the siding from the bottom up just to replace one strip. Not a fun job.
Vinyl discolors where as aluminum does not.
Vinyl can not be painted with any success but aluminum can.
These are just a few of the beefs I have with our vinyl siding.
Hope it helps you decide.

I have a red brick house, with one dormer extension across the top of the front porch, makes the 2 bedroomslarger. This dormer is covered by white aluminum siding. My trim around all windows and porches on this house is white. Can I change the dormer siding to a new color (reddish, to match or accent the brick) without changing color of all trim on this house. Been looking around the neighborhood and can't find any examples. Please Help!!
I am color illiterate.

It will be worse if you try and match the brick because you will NEVER get the right color and it will stick out even worse then the white does.I would instead suggest you accent paint your front door instead. A nice sage green or some type of green family will cause the eye to see the front door..the welcome area and distract your from the dormer. If you want to change the dormer siding maybe try a grey...the same color as the mortar instead. This way is will be softly set into the background instead.

Cover brick molding with aluminum

I have heard there is a aluminum kit you can buy to cover brick molding. It is pre bent and mitered. I heard it was at home depot but they never heard of it. I would like to know where it is available. I have looked on internet with no luck.

I have never heard of a kit either. (not to say it doesn't exist) but.. have you ever used a metal break? It is a long tool for bending metal and can be rented at tool rental places. Buying aluminum flashing of adequate width, you can bend the flashing to whatever shape you need to cover the molding. This is what I do when making the aluminum trim to cover the wood trim when siding a house, and I imagine it would work for you too.